The present invention relates to a cermet film, and particularly to such a cermet film having a high resistivity and a low temperature coefficient of resistivity so as to be useful as a resistor. The cermet film also exhibits high electric field and high temperature stability.
Cermets are well-known mixtures of ceramic and metal particles. When a ceramic, or insulator, and a metal are cosputtered, the resultant cermet film may consist of very small metal granules in an insulating matrix, i.e., metal particles having an average diameter of less than 200A. Cermets have found extensive use as resistors in microelectronic devices, integrated semiconductor circuits and in hybrid thick film circuits. The use of cermet materials permits one skilled in the art to obtain a particular resistivity merely by choosing the proper kind and quantity of ingredients, i.e., ceramic and metal.
For some applications a high resistance, relatively low temperature coefficient of resistivity (TCR) film would be useful. For example, insulating substrates coated with cermet films would make excellent chip resistors for thick film hybrid circuits. High sheet resistivity could then be obtained without the need for mechanical, chemical or laser trimming of long meander paths. Furthermore, for some applications, it may be necessary that the resistive films function at temperatures of 250.degree. C to 300.degree. c and under dc fields of up to 30,000 volts/cm.